Field
The present disclosure relates to an image forming apparatus to which a container containing developer is attachable and from which the container is detachable.
Description of the Related Art
An electrophotographic image forming apparatuses forms an image by using toner stored in a container, When an amount of the toner stored in the container is less than a predetermined amount, an output image with less density is formed. Thus, in this case, a user replaces this container mounted on a mounting portion of the image forming apparatus with another container containing toner.
Used containers that have been refilled with toner have commercially been available, and Japanese Patent Application Laid-Open No. 2007-102024 discusses an image forming apparatus that determines whether a container mounted on a mounting portion is a refilled container. In the case of the image forming apparatus discussed in Japanese Patent Application Laid-Open No. 2007-102024, information indicating that the volume of the toner in the container is zero is recorded in a memory arranged on the container. In addition, when a sensor detects that there is toner in the container, the image forming apparatus determines that this mounted container is a refilled container.
In addition, U.S. Pat. No. 6,415,112 discusses an image forming apparatus that detects an amount of toner stored in a container mounted on a mounting portion based on an output voltage that changes with the amount of the toner present between a plurality of electrodes arranged on the container. The image forming apparatus discussed in U.S. Pat. No. 6,415,112 compares the value of the output voltage with a threshold and detects the amount of the toner based on the comparison result.
However, since density of the toner in a container changes depending on environmental conditions (e.g., the temperature and the humidity), the amount of the toner present between the electrodes may change depending on the environmental conditions. Thus, the threshold to be compared with the output voltage value cannot be determined uniquely.
In addition, physical properties of toner with which a used container is refilled may differ from those of the toner manufactured by the maker that manufactures the image forming apparatus. Thus, even when the output voltage value is compared with the threshold, the image forming apparatus may not determine whether the container mounted on the mounting portion is a refilled container.
Thus, even if information indicating that the volume of the toner is zero is recorded in a memory, the image forming apparatus cannot determine whether a refilled container has been mounted on the mounting portion or another container without toner has been mounted on the mounting portion.